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Polyaniline and poly(p-phenylene vinylene) as active materials for electronic and optoelectronic devices


The aim of this project is to study electronic transport phenomena, and excitation and recombination electronic processes - related to absorption and emission of photons - of thin films of polyaniline (PANI), poly(p-phenylene vinylene) (PPV) and their derivatives. From such unusual properties for polymers, electronic devices will be built: luminescent and photovoltaic diodes, emitting light electrochemical cells, and field-effect transistors. These polymeric materials will be produced in our laboratories, as well as their thin films that will be fabricated by spin-coating and Langmuir-Blodgett techniques. The physical and chemical characterization of the synthesized polymers will be carried out by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), UV-Vis spectroscopy. Thin films will be studied by the following techniques: scanning electromicroscopy (SEM), atomic force microscopy (AFM), UV-Vis spectroscopy, IR spectroscopy and X-ray diffraction). Detailed studies on electronic conduction mechanisms, photoconduction and luminescent effect will be carried out by continuum and alternate conductivity measurements, photoconductivity and time-of-flight techniques, electrically detected magnetic resonance (EDNIR), optical absorption in the UV-Vis region, photoluminescence (PL), electroluminescence (EL) and circular dicroism(CD). The major part of the experiments will be carried out as a function of the temperature. Polymer/metal interface properties also will be studied and the following electronicand/or optoelectronic devices will be built: diodes, electroluminescent diodes (LEC),emitting light electrochemical cell (LEC), photovoltaic diodes, and field effect transistor(FET). Such devices will be fabricated, characterized and, in some cases, a theoretical model will be proposed as an attempt to explain their operation mechanisms. Our research group - Polymer Group Prof. Bernhard Gross - bas a long tradition in the studies of electrical and structural properties of polymeric materials. In the past ten years we have been focused on the understanding of conductive and semiconductive properties of polymers. The more recent studies are related to the fabrication and characterization of thin polymeric films, polymer/metal interface investigations, and to the study of the optoelectronic properties of these thin films. In the last five years, there searchers of the Group of Polymers have published about 50 papers on conjugated polymer properties in indexed scientific magazines, besides several articles presents in International Symposiums and Conferences. This project will also have the collaboration of outside researchers: Dr. Carlos F.0. Graeff from FFCLRP of University of São Paulo (where the EDMR measurements will be realized); Dr. Marysilvia Ferreira from COPPE/Federal University of Rio de Janeiro (where the interfaces studies will be done), and the Group of Sensors and Devices of Amorphous Silicon of the EP/University of São Paulo (where the devices will be characterized). (AU)